Things have gotten hot and heavy between Justin Bieber and Sofia Richie, but big sis Nicole isn't too happy about it, apparently.
According to Radar Online, the former wild child is concerned that Sofia might get caught up in all the Hollywood madness and spiral down a bad path.
A source close to the star said: "Nicole is flipping out right now over the fact that her sister Sofia is dating Justin Bieber.
"Nicole told Sofia that she is just setting herself up for disaster and it has caused a huge rift between the two sisters.
"Sofia told Nicole to just mind her own business."
It's not looking good! We hope they can patch things up.